Does the implementation of clinical practice guidelines for low back and neck pain by physical therapists improve patient outcomes? A systematic review

Background Physical therapy for neck and low back pain is highly variable despite the availability of clinical practice guidelines (CPG). This review aimed to determine the impact of CPG implementation on patient-level outcomes for spinal pain. Implementation strategies were also examined to determine prevalence and potential impact. Methods Multiple databases were searched through April 2021 for studies assessing CPG implementation in physical therapy for neck and low back pain. Articles were screened for eligibility. The Modified Downs and Black checklist was utilized to determine study quality. Due to the heterogeneity between studies, a meta-analysis was not performed. Results Twenty-one studies were included in this review. Implementation strategies were significantly varied between studies. Outcomes pertaining to healthcare utilization, pain, and physical functioning were assessed in relation to the implementation of CPGs. Multiple implementation strategies were identified, with Managing Quality as the most frequently utilized key implementation process. Findings indicate CPG implementation decreased healthcare utilization, but inconsistent results were found with physical functioning and pain outcomes. Conclusions CPG implementation appears to have a beneficial effect on healthcare utilization outcomes, but may not impact pain and physical functioning outcomes. Effective CPG implementation strategies remain unknown, though utilizing implementation framework may improve outcomes. More research is needed to determine the most effective implementation strategies and effects on pain and physical function outcomes. Supplementary Information The online version contains supplementary material available at 10.1186/s43058-022-00305-2.


Introduction
Low back pain (LBP) and neck pain are among the most common musculoskeletal complaints [1] and leading causes for patients to seek medical care [2]. Physical therapists frequently treat patients with low back and neck pain. However, it has been established that there is significant variability in the care provided to patients with low back and neck pain by physical therapists despite the existence of clinical practice guidelines (CPGs) to treat these conditions [3]. CPGs provide evidence-based recommendations to assist decision-making about health interventions [4]. These documents, developed by expert panels, are normally updated every 3 to 5 years or when the available evidence suggests a reformulation of the previous document is necessary [5]. CPGs are designed to support clinician decision-making through recommendations for evaluation and treatment, based on a synthesis of the best available evidence, to improve patient outcomes and guide physical therapists' treatment planning and interventions. Numerous CPGs have been published on the management of LBP, both interdisciplinary and specific to physical therapy, though fewer have been published on the management of neck pain [6,7]. Adherence to CPGs can decrease the use of ineffective treatments, decrease costs of treatment, and improve patient outcomes [8]. Thus the question remains: if adherence to CPGs improves care in patients with LBP and neck pain, why does treatment continue to be variable?
The authors propose that this variability in treatment may be due to the implementation strategy, or lack thereof, of CPGs. A recent systematic review examining musculoskeletal conditions reported that 54% of physical therapists chose treatments recommended by clinical practice guidelines, 43% chose treatments that were not recommended, and 81% chose treatments that have no recommendation [3]. Barriers to the use of CPGs by clinicians include lack of knowledge or awareness of CPGs, lack of access to recommendations, therapist beliefs, and patient expectations [9,10]. These barriers can be overcome with effective, multifaceted implementation strategies targeting both individuals and healthcare systems to promote adherence to trustworthy CPGs [11]. Therefore, the purpose of this systematic review is to critically synthesize the literature regarding the implementation of CPGs for low back and neck pain in order to answer: (1) Does the implementation of guidelines by physical therapists improve patient outcomes for patients seeking care for low back and neck pain? and (2) Does the implementation strategy of CPGs impact outcomes?

Data sources and searches
The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed during the search and reporting phase of the research process [12]. The review was not registered, nor was a protocol prepared. A comprehensive literature search was performed in four electronic databases (MEDLINE, CINAHL, SCOPUS, and Embase) from inception to April 2020 and updated in May 2021. There exists significant overlap between SCOPUS and Web of Science, and therefore, we chose to only search SCOPUS [13]. OVID and PubMed exist as interfaces for the same database, MEDLINE; thus, only one interface needs to be searched in order to capture MEDLINE content. Cochrane was not searched as all published CPGs and randomized control trials are also indexed in MEDLINE. Grey literature was not searched and may be a limitation to this review. The literature search plan was developed and performed in collaboration with a Medical Librarian. The search was developed using keywords and subject headings, appropriate for each database, related to neck and/or back pain, as well as clinical practice guideline implementation. See Additional file 1.

Selection criteria
Articles were eligible for study inclusion if they met the following criteria: (1) studies in which physical therapists or physiotherapists provided care for patients with neck and/or LBP, (2) patients were 18 years of age or older, (3) the physical therapists used published clinical practice guidelines for the management of neck or low back pain, (4) study designs included randomized clinical trials, observational cohort studies, and case reports published in English, and (5) included at least one outcome assessing pain, patient-reported physical functioning or disability, or healthcare utilization (HCU). We included all data pertaining to PT or other healthcare visits or associated costs Page 3 of 31 Fillipo et al. Implementation Science Communications (2022) 3:57 and medication or procedure usage or costs associated with low back or neck pain under healthcare utilization.

Study selection and data extraction
Databases were systematically searched in April 2020 and updated in May 2021. All search results were imported into Covidence (Veritas Health Innovation, Melbourne, Australia). After duplicates were deleted, the titles and abstracts were screened by two reviewers (BR, RF), while one reviewer (KP) resolved any conflicts that arose between the two reviewers. References in systematic reviews were hand searched for additional articles. Full texts of the remaining articles were then screened by two reviewers (JM, RF), while one reviewer (MC) resolved any conflicts. Six reviewers (BR, JM, KP, MC, RF, DC) performed data extraction on the final studies included in the review. Each study had a primary data extractor and another author who checked for accuracy and completeness. A data extraction template was created. Each reviewer extracted this data from their assigned studies and input it into the template. The second assigned author checked for accuracy and completeness. See Fig. 1 for article selection.

Data analysis
For this review, we descriptively reported our findings and did not perform a meta-analysis due to the lack of homogeneity of study designs and reported data across studies. We included all data reported in each study. First, we reported the study designs, study settings, sample sizes, and country where the studies were performed. Next, we examined the implementation processes and the implementation strategies for the guidelines that the studies reported. One challenge in implementation literature is that implementation strategies are not always clearly defined and there is often inconsistent language utilized. In an effort to clearly differentiate implementation strategies, we used the compilation by Powell et al. [14], which details six key implementation processes and 68 discrete, or individual, implementation strategies. The six key implementation processes represent larger overarching implementation processes and include planning, educating, restructuring, financing, managing quality, and attending to the policy context [14] and the 68 discrete implementation strategies are each classified under one of the key implementation processes. In this  framework, planning includes strategies aimed at gathering information, selecting strategies, building buy-in, initiating leadership, and developing relationships. Educating strategies aim to inform individuals and include developing materials, educating, educating through peers, and informing and influencing stakeholders. Financing includes discrete strategies modifying incentives and facilitating financial support. Restructuring includes strategies addressing roles, sites, and systems. Managing quality includes putting strategies and systems in place to evaluate and improve quality. Attending to the policy context includes addressing requirements, laws, and standards. Using this compilation by Powell et al. [14] allowed for assessment of implementation strategies at both a broad level using the key processes and a focused level using the specific strategies. One reviewer (MC) retroactively assigned the discrete implementation strategies and key implementation processes to each study based on reviewer interpretation of the implementation process described in each and one reviewer (RF) checked for accuracy and completeness. Lastly, we examined primary and secondary clinical outcomes pertaining to HCU, pain, and patient-reported physical function and disability. HCU included healthcare visits, healthcare costs, physical therapy visits and physical therapy costs, procedural interventions, medication utilization, and imaging. Physical function and disability were assessed using patient-reported outcomes including Roland-Morris Disability questions, Oswestry Disability Index, Patient-Reported Outcomes Measurement Information System (PROMIS), or other measures as indicated by the study. Studies were organized according to the outcomes assessed.

Quality assessment
Risk of bias was assessed using the Downs and Black checklist for internal consistency among the different study types included, without considering the power analysis. This has been shown to be a reliable and valid tool for measuring the methodological quality of randomized and nonrandomized studies [15]. Two reviewers (RF, BR) evaluated each study independently. A third reviewer (DC) settled any discrepancies between the primary reviewers.

Risk of bias
The majority of the studies included were of moderate risk of bias, with one study [36] at high risk of bias. Only three studies had a low risk of bias [26,27,29], scoring at least 22 points on the Downs and Black checklist.

Study population
Nineteen studies assessed the impact of guideline implementation in patients with LBP [16-18, 20-27, 29-36] and two studies assessed guideline implementation in patients with neck pain [19,28]. Of the studies that assessed guideline implementation and LBP, two specifically included only back-related leg pain [27,31] and three included only acute LBP [17,18,20]. The remaining studies examined patients with non-specific LBP. Of the two studies analyzing guideline implementation and neck pain, one study specifically assessed application in patients with acute whiplash-associated disorders (WAD) [28]. Sample sizes in the studies examined ranged from 40 to 753,540 patients, with higher sample sizes found in the retrospective cohort studies.

Study setting
Seven studies were conducted in the USA [16-20, 34, 36], six studies were conducted in the Netherlands [21,24,25,29,31,35], and two studies were conducted in Canada [28,30]. The remainder of the studies were conducted in Nepal [26], Denmark [32], Sweden [23], and Australia [27]. Two did not report a country as they were conducted in global military health systems [16,33]. Five studies were conducted in private practice clinics [16,18,21,29,35], two studies were conducted in military treatment centers [16,33], and one study was conducted based on a review of workers compensation [20]. The remainder of the studies were conducted in the outpatient setting.

Health care utilization Cost
Eighteen studies [16-28, 31, 33-36] assessed HCU as an outcome. Eight studies [16, 18-20, 22, 24, 25, 33] assessed total healthcare costs, and six studies [17-19, 24, 25, 36] assessed PT episodes of care costs only. All studies assessing costs relative to guideline adherence found decreased costs for guideline adherent care except one [19], which found no difference between groups for non-PT healthcare costs. Hoeijenbos et al. [25] found no significant differences in cost between active and standard guideline implementation except for a difference in healthcare costs at the 6-week mark. Standard implementation involved passive dissemination of guidelines, whereas active implementation involved two training session in addition to the standard implementation [25]. One study [24] found significantly lower costs for patients receiving guideline-based care compared to an intensive group training protocol ( Table 2).

Visits
Eight studies [17,18,23,24,26,27,30,33] assessed the total number of healthcare visits, fifteen studies [16-19, 21-28, 34-36] assessed the number of PT visits, and four studies [17,18,23,34] assessed the duration of PT care. One study [16] identified predictors of PT utilization for patients with low back pain, including higher index visit copayment, not receiving long-term disability, greater number of diagnosis codes at index visit, and not having comorbid neck/thoracic pain. Of the six studies assessing visits relative to guideline adherence, four [17][18][19]35] found significantly decreased visits for guideline adherent care. The other two [22,36] found similar trends but did not perform a statistical analysis. Outcomes pertaining to visits can be found in Table 3.
Two studies [31,34] involved care pathways that encouraged early utilization of PT. Non-PT healthcare visits were reduced in both studies. One of the studies [34] found no differences in the number of PT visits; however, the duration of care was decreased for those that received guideline-based care. Combining guideline-based advice with an individualized functional restoration program resulted in significantly less non-PT healthcare visits in one study [27] but the number of PT visits to support this protocol was significantly higher. HCU rates did not appear to be significantly impacted by factors such as guideline delivery (active versus standard) [25], the addition of intensive group training [24] or symptom chronicity (acute versus chronic) [21]. There was also no significant difference between groups when comparing visits for a pain education group and guideline-based PT [26].

Imaging
Five studies [18,19,22,24,34] reported on utilization of imaging, as seen in Table 4. Three studies reported decreased imaging utilization rates for guideline adherent care compared to nonadherent care [18,19,22]. One study [34] found that participants in the Rapid Access program were less likely to have lumbar radiographs or advanced imaging over the 6-month follow-up period compared to nonparticipants. The addition of an intensive training protocol to guideline-based care did not significantly impact imaging utilization [24].

Medication
Full results on medication utilization and costs can be found in Table 4. Eight studies [16,18,22,[24][25][26][27] reported on medication utilization and/or cost. Guideline adherence resulted in decreased prescription medication costs in one study [22], significantly fewer prescription medications in two studies [18,19], and decreased skeletal muscle relaxants in one study [18]. The addition of an intensive group training protocol to guideline-based care [24] and method of guideline delivery (active versus standard) [25] did not significantly impact medication use. Similarly, there was no significant difference in medication use between groups receiving individualized functional restoration and guideline-based advice aside from the proportion taking Paracetamol at 12 months [27]. Statistical analysis was not performed in two studies thus limiting comparisons [16,26].

Procedures
Five studies [16,18,22,27,34] reported on procedure utilization, as demonstrated in Table 4. Patients receiving guideline adherent care were significantly less likely to have diagnostic procedures, injection procedures,  and epidural injections with fluoroscopy in one study [18], and had decreased likelihood of surgery and receiving injection in another study [16]. A third study [22] reported that guideline adherent care resulted in decreased lumbar spine injections and lumbar spine surgeries. Magel et al. [34] found participants receiving PT via Rapid Access were significantly less likely to receive epidural steroid injections compared to nonparticipants. Statistical analysis was not performed in one study [27].

Pain
Twelve studies [17-19, 23, 24, 26-30, 32, 35] included assessment of pain ( Table 5). The primary outcome measure was the numeric pain rating scale (NPRS) or numeric rating scale (NRS), utilized in all but one study [35]. Five studies [17][18][19]23, 35] compared pain           outcomes with guideline adherence. Two of the studies [17,18] found a statistically significant difference favoring adherent care. Schroder et al. [23] found similar results at 3 and 6 months but no difference between groups at 12 months. Rutten et al. [35] found no association between percentage of guideline adherent care and pain with the exception of the chronic low back pain subgroup, which demonstrated a medium to large negative correlation.
One study [19] found a statistically significant difference favoring nonadherent care. Sharma et al. [26] reported that the addition of pain education to guideline-based care resulted in significantly less pain compared to guideline-based care alone. Hahne et al. [27] found that the addition of individualized functional restoration training to guideline-based advice resulted in significantly lower back pain at 10 weeks but no difference between groups at the end of year 1. Three studies [24,28,29] found no statistically significant differences between groups for pain outcomes when comparing method of guideline delivery [29], government-regulated guidelines [28], and addition of intensive training to guideline-based care [23]. Two studies [30,32] did not assess statistical significance across groups.

Physical functioning and disability
Fourteen studies [17-19, 22-30, 32, 35, 36] reported patient-level outcomes related to function; for full results refer to Table 6. The most prevalent functional measure utilized was the Modified Oswestry Low Back Pain Disability Index (ODI). Guideline adherent care resulted in significant improvement in function in four of five studies [17,18,30,35] that assessed significance in patients with LBP when utilizing the ODI as the primary measure. However, one [30] did not utilize a control or comparator. Guideline adherence did not significantly impact function in one study that included patients with neck pain [19].
One study [27] reported that the addition of an individualized restoration program to guideline-based advice resulted in significantly improved function at 10 weeks and 52 weeks compared to guideline-based advice alone. Sharma et al. [26] reported that the addition of pain education to guideline-based care resulted in significant improvement in sleep. There was no significant difference between groups when compared to guideline-based care alone. The remaining studies did not find significant between-group differences or did not include a control group, except for one [25] who reported baseline differences between groups which disappeared after 6 weeks.

Discussion
The purpose of this systematic review was to determine the influence of guideline implementation on clinical outcomes of pain, physical function/disability, and HCU metrics in patients seeking physical therapy for neck and/or low back pain. Implementation strategies for CPGs were also examined to determine the variance in the focus of implementation strategies on success of the implementation. Our review identified a number of approaches to guideline implementation, with the most common implementation process being Managing Quality. This is largely due to the frequency with which "audit and provide feedback" was utilized, a discrete implementation strategy under the Managing Quality key implementation process. Educating was frequently utilized as many implementation methods included dissemination of guidelines and educational material. When we examined the relationship of implementation of CPGs and clinical outcomes, we found that, across studies, implementation and adherence to guidelines was beneficial for decreased HCU, including decreasing costs, total number of healthcare visits, medications, and procedural interventions. However, there were inconsistent findings for the benefit of guideline implementation for improvements in pain and function in patients. Pain improved in all groups studied, but results did not appear to favor guideline implementation. Full comparisons of physical function and disability outcomes were difficult to compare due to lack of consistency in measures utilized.

Guideline implementation
Few studies assessed the effects of types of guideline implementation, or utilized controls or comparators for implementation strategy, and more evidence is needed to evaluate the most effective guideline implementation strategies to improve patient outcomes. Only two articles [25,29] in our review, reporting on one study, assessed the impact of active versus passive guideline implementation and found no difference in patient outcomes between groups. When assessing HCU, the authors concluded that there may be some benefit to active implementation, but the results were small and did not lend clear support to use of an active strategy when considering the cost of implementation. Additional studies in this review could be classified as active, including engagement of stakeholders, or passive, including only dissemination of materials, implementation, but did not compare active and passive interventions within the same study.
Previous systematic reviews have identified active, multifactorial implementation strategies as more effective [37,38]; however, a more recent review [39] found no benefit to an active over passive implementation. Additionally, a recent review by Mesner [40] indicated that discrete, utilizing only a singular implementation strategy, or multifaceted, utilizing multiple strategies implementation strategies may not be the best indicators of guideline uptake, rather the duration of the implementation program may better predict this. Powell et al. [14] propose an additional distinction when using more than one implementation strategy. The authors suggest distinguishing between multifaceted strategies and blended strategies, defined as multifaceted strategies that address "multiple levels or barriers to change" and are "packaged as a protocolized and branded implementation intervention" (p. 125). Implementation frameworks could be utilized to satisfy this definition.
The use of an implementation framework, model, or theory can aid in both intervention design and assessment of outcomes in the formulation of a blended implementation intervention [41]. Several included studies utilized published implementation frameworks to guide their intervention, while others utilized theories such as the behavior change theory, learning theory, and change management theory to structure their intervention. Utilizing a theory-informed implementation strategy is proposed to improve implementation outcomes [42] but often explanations for the theoretical basis are lacking  [43]. In our review, few stated a rationale for their choice.
To aid in this decision-making, implementation frameworks are often structured around different aims within the implementation process [41]. Some authors [44] suggest utilizing multiple frameworks for a more comprehensive approach, for example, using one framework for guiding the implementation process and one for evaluating outcomes. The use of an implementation framework or model promoted the use of the strategy "tailor strategies to overcome barriers and honor preferences, " and studies utilizing this typically demonstrated improvement in outcomes over time in our review. This suggests this may be a beneficial strategy for implementation. The remaining included studies failed to incorporate assessment of barriers and subsequent tailored strategies. Comprehensive, blended strategies, including barrier assessment, may be beneficial as these may more efficiently address the obstacles and needs of the involved stakeholders and should be further investigated.
Audit and provide feedback was utilized in almost every included study. However, the majority of the studies utilized this method to assess adherence, rather than to inform clinicians of their progress. One study [45] suggests this strategy is most effective when employed in a timely, personalized, and non-punitive manner. Since the majority of studies utilizing this strategy did not provide individualized feedback, rather using the information as an aggregate measure, improvement in providers' adherence and thus patient outcomes is less likely. Though we did not assess therapist adherence as a measure in our review, it is worth noting the impact this may have had on outcomes.

Adherence
Implementation of guidelines does not guarantee provider adherence to guidelines or a change in provider practice. One study [46] utilizing an implementation framework by Grol et al. [47] found guideline adherence to increase frequent use of guidelines to only 55%, and a review by Al Zoubi et al. [37] indicated that multifaceted interventions may increase provider adherence, but with mixed effects. Factors that may influence uptake of CPGs include therapist beliefs and patient beliefs or expectations [48], and implementation strategies may have little effect on patient outcomes if therapists are providing guideline adherent care at baseline. Other authors [49] suggest that the duration of the implementation strategy may be insufficient to produce long-term changes in practice and patient outcomes. Additionally, adherence was measured inconsistently between studies in this review. Defining and utilizing a singular assessment may provide better insight into provider adherence.
Providers report numerous barriers to guideline adherence including patient preference [50]. However, most CPGs now recommend patient-centered care and shared decision-making (SDM) as an important component of care, thus placing greater emphasis on patient preference [51]. Guidance for implementation of SDM has been identified as an area that is lacking [52] and was typically not assessed as a component of adherence in the included studies. Improving the application of SDM in guideline adherent care may improve patient outcomes and satisfaction with treatment.
In addition to the above, it is worth considering the source of the guidelines. The quality of the evidence the guidelines are created from may impact outcomes and adherence [53]. In this review, we included studies assessing implementation of any published guideline. Therefore, there may be a difference in quality and outcomes based on the guidelines assessed.
Finally, though improving adherence to guidelines through implementation strategies may improve quality of care in neck and low back pain, a change in patient outcomes may be difficult to assess. This could be due to the generally favorable outcomes of acute low back [54] and neck pain [55]. Therefore, using HCU as a proxy assessment of quality of care may be appropriate. As noted above, delineating chronicity of pain may also be of use in future studies.

Healthcare utilization
Similar to our findings, a systematic review by Hanney et al. [56] found that guideline adherence reduced HCU in patients treated for LBP. Our systematic review added additional data from thirteen new studies. These studies provided further support for the benefit of reducing HCU when adhering to guidelines. Moreover, our systematic review also captures findings from studies that have investigated the impact of guideline adherent care for neck pain. Furthermore, new studies included in our review included the assessment of guideline-based care in conjunction with additional treatments.
A plausible reason for the reduction in healthcare costs, healthcare visits, and resource utilization may be in part because many guidelines recommend fewer visits (typically three or less) for acute low back pain, instead promoting independence through reassurance and advice to remain active [17,21]. Thus, guideline adherent care would trend toward fewer physical therapy visits and subsequently lower costs, as demonstrated in this review. However, reduction in physical therapy visits alone does not account for the reduction of non-physical therapy-related HCU.

Pain and function
Pain and function improved in all groups in the included studies. Of the included studies assessing pain, only two found significant improvements favoring guideline implementation. The lack of improvement in patientreported function and pain following guideline implementation is consistent with findings in other reviews [37,49,57]. Some authors [29] have suggested this lack of improvement may be due to high-quality care already provided by physical therapists. Others [37] have stated this may be due to additional patient characteristics, such as fear-avoidance behaviors that limit change. This may be supported by one study [26] which compared guideline-based care plus pain education to guidelinebased care alone and found greater improvements in pain in the intervention group. Emerging evidence suggests that there may be a benefit of including new treatment approaches within guideline adherent care. Of note, several studies assessed impacts in relation to chronicity of LBP. Two studies [17,18] found greater improvements in acute low back pain with guideline adherence, whereas one study [35] found a significant effect on pain in patients with chronic low back pain. This suggests that subgroup analyses for chronicity of low back pain should be considered in future studies.
In our review, five studies [17,18,27,33,35] found a significant difference in patient-reported functional outcomes favoring guideline adherent care. Of these, only one study [33] compared implementation to a no-implementation control group and found no significant difference in functional outcomes. The remaining studies did not compare implementation strategies or have a control group. Therefore, it is difficult to determine the efficacy of implementation strategies on functional outcomes.
The ability to compare functional outcomes across studies is limited due to the lack of consistent outcome measures utilized. It is important to note that the majority of the studies that found improvements favoring guideline adherence used the ODI as the primary functional outcome measure. A recent review indicated that most patient-reported outcome measures assessing physical functioning in low back pain were insufficient to garner a full understanding of the patient's physical functioning [58]. Another study recently found that the RMDQ and ODI cannot be used interchangeably [59]. Determining a valid and reliable physical functioning measure to utilize across studies will aid in determining effectiveness of implementation.

Neck pain
Only two of the 21 included studies assessed guidelines associated with neck pain. One study assessed chronic neck pain [19], and one assessed WAD [28]. One study [19] found that the group that received nonadherent care had greater improvements in pain, but no difference in functional outcomes. More research is needed to assess the impact of guideline implementation and adherence on patient outcomes in patients with neck pain.

Future research
The results of this review suggest guideline implementation and adherence may decrease HCU, but the results are inconclusive when comparing pain and physical function outcomes. However, as only one study used a no intervention comparator, the true effect of the implementation strategies is unknown and should be further investigated. Due to the limited studies identified, future research should also focus on implementation of guidelines in neck pain.

Strengths
This systematic review is the first to our knowledge that assesses the impact of physical therapist implementation of CPGs on patient-level outcomes in back and neck pain. Our search strategy was thorough and able to capture as many eligible studies as possible. We utilized Powell et al. [14] to classify implementation strategies as we found this to be the most comprehensive, incorporating the elements of the Effective Practice and Organization of Care (EPOC) system, a checklist for systematic reviews. The EPOC system requires many studies to be excluded based on study design. Therefore, by utilizing the Powell et al. classification system, we were able to include a greater number of studies.

Limitations
Several limitations to this review exist. There was significant heterogeneity across studies related to the type of implementation, the interventions used, and measured outcomes, limiting the ability to effectively synthesize the results. We utilized a broad definition of implementation during our inclusion process to better capture current practice. However, it is unlikely that a more narrow definition would have significantly reduced the heterogeneity encountered.
Because we utilized the classification system proposed by Powell et al. [14], additional studies qualified for inclusion compared to similar, previous studies. Key implementation processes and implementation strategies were assigned based on reviewer interpretation of included study articles and therefore some nuances of implementation may have been missed. We excluded studies that assessed effectiveness of implementation via vignettes as we did not find this to be

Conclusion
In conclusion, guideline implementation in physical therapy treatment of low back and neck pain has a positive effect on HCU, but more research is needed to determine the effect on pain and function. This may be further elucidated by analyzing chronicity of pain separately. Additionally, utilizing a uniform outcome measure to assess function may further highlight the effect of implementation, or lack thereof. The most effective implementation strategy is unknown, but use of blended or published implementation frameworks may help guide effective strategies. However, the reduction in HCU, without sacrificing pain and functional outcomes, improves the value of care provided and demonstrates the benefits of guideline implementation.
Additional file 1. Search Strategy Report.